Vertical milling machines are known in the art and a number of different types of milling machines are commercially available. By way of example, Bridgeport® and RF Rong Fu® produce various models of milling machines. These commercially available milling machines are generally classified into two main divisions, vertical and horizontal. In the horizontal milling machines, the cutter is horizontally mounted to a spindle and moves in a horizontal manner. Similarly, in a vertical milling machine, the cutter is vertically disposed and moves in a vertical fashion.
A conventional vertical milling machine generally includes a table on which a workpiece can be supported, and a quill that supports a tool or cutter for movement toward and away from the table for milling the workpiece. Typically, the table is adjustable within the horizontal plane from side to side and from front to back relative to the quill. Although many milling machines are manual, in the sense that adjustment of the table and movement of the quill is manually achieved, improvements in the art have been made for fully automated machines. These automated machines provide some advantages over manual machines, however, they are considerably more expensive for users. Moreover, they lack the versatility of manual machines.
In addition to the above, many of the manual, vertical milling machines commercially available provide an already attached manual measuring apparatus for determining the vertical travel, or milling depth, of the quill. By way of example, RF Rong Fu® milling machines provide a plastic assembly located on the face of the machine. The assembly comprises a housing attached to the milling machine and a moveable indicator attached to a quill shaft stop bar. The housing further has a rectangular hole which is centrally located thereon and a measurement scale surrounding the hole. As the quill is lowered and raised the indicator points to a corresponding measurement on the measurement scale, thereby informing a user of the approximate vertical movement or depth.
A disadvantage of the current measuring devices provided in milling machines is that they do not provide precise measurements. Typically, the units of measure on the devices are not small enough and one's ability to properly bore holes and mill workpieces is restricted. An example of an industry that thus is restricted is the steel industry, in which machined parts must be milled to precise tolerances. The measuring units currently provided simply do not and cannot accurately measure pieces to ensure that certain hole depths meet those tolerances. Thus, a need exists for an apparatus which provides a precise measurement of the depth or vertical movement of a quill.
Currently, there exist some measuring devices which accurately determine the vertical movement of the quill. However, for various reasons, these devices are ineffective to accomplish the objects stated herein. For example, the Mitutoyo Corporation manufactures the Digimatic Quill Kit for vertical Bridgeport® milling machines and Bridgeport® type machines. The Quill Kit essentially is a retrofitted housing comprising a main scale, a digital display indicator attached to the front surface of the main scale, a rear support plate secured to the rear of the indicator, thereby securing the indicator to the main scale, a tapped hole mounting bracket which is attached to the scale, a base, a scale stop bar that is mounted to the rear plate, a scale stop bracket and a plurality of screws and washers. The Quill Kit unit is attached to a milling machine by first retracting the spindle of the machine and removing the quill wheel. Vernier scale screws of the milling machine are removed and the base is placed over the vernier scale. The vernier screws are replaced and the mounting bracket is attached to the base. The scale is attached to the mounting bracket by the scale stop bracket.
A disadvantage of the Quill Kit is that it is only useful for Bridgeport® type machines. The device simply cannot be used on other types of milling machines, such as the RF Rong Fu® models. Moreover, the Quill Kit is comprised of many unnecessary components. As such, it is expensive to manufacture.
Stops and guides for use on drilling, depth milling and other similar machinery are known, as are quick release nuts which provide for selective sliding or threading motion with respect to a threaded shaft. Guthrie U.S. Pat. No. 4,693,656 describes such devices. Current stops, as shown by Guthrie, have a spring which presses against the end of the release nut, causing the stop to remain in place. However, such arrangement is not sufficiently tight to prevent movement of the stop on the threaded shaft or rod.
Thus, it is clear that a need exists for an inexpensive, stop which can hold be tightly when desired, and which can be provide both coarse and fine adjustments, and which is simple and versatile, and readily retrofit for use with vertical milling machines, and which is readily removable.